The Elevation Profile tool in MapBrowser allows you to draw a line (or path) across an area of interest and visualise the elevation along the selected line in the Vertical and True Ortho base layers. In these base layers, MapBrowser displays the following types of elevation data:
- Only DSM if the survey has been captured using Nearmap's first generation camera system
- DSM and DTM/DEM if the survey has been captured using Nearmap's second generation camera system
Typically, both DSM and DTM/DEM elevation are displayed for True Ortho imagery.
Accessing the elevation profile
To access the elevation tool in MapBrowser, draw a line or path. Select the object you have drawn, and select the Elevation Profile option from the Display menu. A panel containing a graph of the elevation from one end of the line/path to the other is displayed. The starting point of the path you created is on the left.
You can switch between surveys to see the changes in elevation data over time. If a survey does not have elevation data, a message is displayed to indicate that. You can then click CHANGE SURVEY DATE to view the most recent survey that has elevation information for the selected location.
The following information is displayed:
- Data Source
- Minimum, maximum and average elevation along the line or path
- Minimum, maximum and average slope. To understand how slope is calculated, refer to this article.
The resolution of the data in the elevation profile is indicated next to the data source, which can be one of the following:
- 'low-res', meaning accuracy can vary between surveys and is indicative only.
- 'high-res', indicating that the survey has been captured using our second generation camera system, and the accuracy of elevation data is in line with Nearmap's accuracy specifications.
Move your cursor along the graph as shown below, and a tooltip will appear showing the elevation, distance and slope along the path for that location.
Basis of profile
The Nearmap data is calculated based on imagery, so the elevation values you see are based on a Digital Surface Model rather than a Digital Terrain Model. Consequently the Nearmap elevation will more closely represent the tops of buildings rather than the ground underneath (please note the Nearmap data is not currently recommended for determining building height).